This invention relates generally to thermoplastic packaging, and more specifically to packaging laminates for food products.
It is common practice to package articles such as food products in thermoplastic films or laminates to protect the product to be packaged from abuse and exterior contamination, and to provide a convenient and durable package for transportation and ultimate sale to the end user.
Thermoforming and other similar techniques are well known in the art for packaging food products. Suitable thermoforming methods, for example, include a vacuum forming or plug-assist vacuum forming method. In a vacuum forming method, the first web is heated, for example, by a contact heater and a vacuum is applied beneath the web causing the web to be pushed by atmospheric pressure down into a preformed mold. In a plug-assist vacuum forming method, after the first or forming web has been heated and sealed across a mold cavity, a plug shape similar to the mold shape impinges on the forming web and, upon the application of vacuum, the forming web transfers to the mold surface.
After the forming web is in place, a product is placed, such as by manual loading, on the forming web and a second, substantially non-forming web is disposed over the product. At a sealing station, the packages vacuumize and fusion seal with a sealing device such as a heated jaw. The first or forming web encloses a substantial portion, generally more than half, of the product to be packaged.
Thermoforming is a popular method of packaging meat products such as bacon. In packaging such products, it is desirable to provide a clear package with good optical properties such as clarity and gloss in order to enhance package appearance for the consumer.
Color retention of the product, particularly in the case of meat products, and extended shelf life are also advantageous features.
Finally, it is desirable to provide a packaging material, which, after the thermoforming operation, will maintain a tight package appearance, commonly known in the art as good memory characteristics.
It is, therefore, an object of the present invention to provide a thermoplastic laminate having good optical properties such as clarity and high gloss.
It is also an object of the present invention to provide a thermoplastic laminate for packaging food products wherein good color retention and shelf life are obtained.
It is yet another object of the present invention to provide a thermoplastic laminate characterized by good oxygen barrier properties over an extended shelf life.